Steady upticks of land and ocean surface temperatures have pushed 2013 squarely into the top 10 warmest years since 1880, when scientists began recording weather data. The globe’s combined annual temperatures have topped the 20th century’s average for 37 years in a row.

In an annual climate and weather analysis released January 21, the National Oceanic and Atmospheric Administration reported that last year’s temperatures rose 0.62° Celsius above the 20th century’s averag...